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Solutions: Definitions, Types, and Solubility

This article provides an overview of solutions, including their definitions, types, and the factors that affect the rate of dissolution. It also discusses concentration, solubility, and colligative properties, as well as the properties, uses, and strength of acids and bases.

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Solutions: Definitions, Types, and Solubility

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  1. Ch. 24 - Solutions I. How Solutions Form Definitions Types of Solutions Dissolving Rate of Dissolving

  2. A. Definitions • Solution - homogeneous mixture Solute - substance being dissolved Solvent - present in greater amount

  3. A. Definitions Solute - KMnO4 Solvent - H2O

  4. B. Types of Solutions • Based on state of solvent. • All solid-liquid-gas combos are possible. • EX: dental amalgam (alloy of silver, mercury, etc.) • liquid solute, solid solvent • solid solution

  5. C. Dissolving • Solvation • occurs at the surface of the solute • solvent particles surround solute particles (+/- attraction) • solute particles are pulled into solution

  6. C. Dissolving NaCl dissolving in water

  7. D. Rate of Solution • Solids dissolve faster... • more stirring • small particle size(increased surface area) • high temperature

  8. D. Rate of Solution • Gases dissolve faster... • no shaking or stirring • high pressure • low temperature

  9. Ch. 24 - Solutions II. Solubility & Concentration

  10. A. Concentration • Concentrated solution • large amount of solute • Dilute solution • small amount of solute

  11. A. Concentration • % by Volume • usu. liquid in liquid • EX: 10% juice = 10mL juice + 90mL water • % by Mass • usu. solid in liquid • EX: 20% NaCl = 20g NaCl + 80g water

  12. UNSATURATED SOLUTION more solute dissolves SATURATED SOLUTION no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form A. Concentration concentration

  13. B. Solubility • Solubility • maximum grams of solute that will dissolve in 100 g of solvent at a given temperature • varies with temperature • based on a saturated solution

  14. B. Solubility • Solubility Curve • shows the dependence of solubility on temperature

  15. B. Solubility • Solids are more soluble at... • high temperatures. • Gases are more soluble at... • low temperatures. • high pressures (Henry’s Law).

  16. Ch. 24 - Solutions III. Particles in Solution “Like Dissolves Like” Electrolytes Colligative Properties

  17. NONPOLAR NONPOLAR POLAR POLAR A. “Like Dissolves Like” • Detergents • polar “head” with long nonpolar “tail” • can dissolve both types

  18. - + - - + + acetic acid salt sugar B. Electrolytes Weak Electrolyte Electrolyte Non- Electrolyte solute exists as ions and molecules solute exists as ions only solute exists as molecules only

  19. B. Electrolytes • Dissociation • separation of +/- ions when an ionic compound dissolves in water

  20. B. Electrolytes • Ionization • breaking apart of polar covalent molecules into ions when dissolving in water

  21. C. Colligative Properties • properties of solutions that depend only on solute concentration • Freezing Point Depression • solutes lower the f.p. of a solvent • Boiling Point Elevation • solutes raise the b.p. of a solvent

  22. C. Colligative Properties Freezing Point Depression View Flash animation.

  23. C. Colligative Properties Boiling Point Elevation Solute particles “get in the way.”

  24. C. Colligative Properties • Effect increases as the solute concentration increases. • Uses: • antifreeze • making ice cream • salting icy roads

  25. Ch. 24 - Acids & Bases IV. Intro to Acids & Bases Definitions Properties Uses

  26. A. Definitions • Acids • Ionize to form hydronium ions (H3O+) in water HCl+ H2O  H3O+ + Cl–

  27. A. Definitions • Bases • Dissociate or ionize to form hydroxide ions (OH-) in water NH3+ H2O  NH4+ + OH-

  28. A. Definitions • Indicator • substance that changes color in an acid or base • Examples: • litmus - red/blue • phenolphthalein - colorless/pink • goldenrod - yellow/red • red cabbage juice - pink/green

  29. sour taste corrosive electrolytes turn litmus red react with metals to form H2 gas bitter taste corrosive electrolytes turn litmus blue slippery feel B. Properties ACIDS BASES

  30. H3PO4 - soft drinks, fertilizer, detergents H2SO4 - fertilizer, car batteries HCl - gastric juice HC2H3O2 - vinegar C. Uses ACIDS

  31. NaOH - lye, drain and oven cleaner Mg(OH)2 - laxative, antacid NH3 - cleaners, fertilizer C. Uses BASES

  32. Ch. 24 - Acids & Bases . Strength of Acids & Bases Strong vs. Weak pH

  33. Ch. 24 - Acids & Bases V. Intro to Acids & Bases Definitions Properties Uses

  34. A. Definitions • Acids • Ionize to form hydronium ions (H3O+) in water HCl+ H2O  H3O+ + Cl–

  35. A. Definitions • Bases • Dissociate or ionize to form hydroxide ions (OH-) in water NH3+ H2O  NH4+ + OH-

  36. A. Definitions • Indicator • substance that changes color in an acid or base • Examples: • litmus - red/blue • phenolphthalein - colorless/pink • goldenrod - yellow/red • red cabbage juice - pink/green

  37. sour taste corrosive electrolytes turn litmus red react with metals to form H2 gas bitter taste corrosive electrolytes turn litmus blue slippery feel B. Properties ACIDS BASES

  38. H3PO4 - soft drinks, fertilizer, detergents H2SO4 - fertilizer, car batteries HCl - gastric juice HC2H3O2 - vinegar C. Uses ACIDS

  39. NaOH - lye, drain and oven cleaner Mg(OH)2 - laxative, antacid NH3 - cleaners, fertilizer C. Uses BASES

  40. - - + + A. Strong vs. Weak • Strong Acid/Base • 100% ions in water • strong electrolyte • HCl, HNO3, NaOH, LiOH • Weak Acid/Base • few ions in water • weak electrolyte • HC2H3O2, NH3

  41. 14 0 7 INCREASING BASICITY INCREASING ACIDITY NEUTRAL B. pH Scale • pH • a measure of the concentration of H3O+ ions in solution • measured with a pH meter or an indicator with a wide color range

  42. B. pH Scale pH of Common Substances

  43. ConcepTest • Which of the following "molecular" pictures best represents a concentrated solution of the weak acid HA? A B

  44. ConcepTest • Is the following statement TRUE or FALSE? • A strong acid has a lower pH than a weak acid. • FALSE - Strong/weak refers to amount of ionization whereas pH refers to concentration of H+.

  45. Ch. 24 - Acids & Bases VI. Neutralization • Neutralization Reaction • Titration

  46. A. Neutralization Reaction • Chemical reaction between an acid and a base. • Products are a salt (ionic compound) and water.

  47. = A. Neutralization Reaction ACID + BASE  SALT + WATER HCl + NaOH  NaCl + H2O Neutralization does not always mean pH = 7.

  48. KOH + HNO3 H2O + KNO3 A. Neutralization Reaction Acid? Base? Salt? HNO3 KOH KNO3

  49. standard solution unknown solution B. Titration • Titration • Process in which a standard solution is used to determine the concentration of an unknown solution.

  50. B. Titration • Endpoint (equivalence point) • Point at which equal amounts of H3O+ and OH- have been added. • Determined by… • indicator color change • dramatic change in pH

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